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[Xen-devel] [PATCH v5 4/6] libxl: change xs path for QEMU



Change the QEMU xenstore watch path to
/local/domain/$LIBXL_TOOLSTACK_DOMID/device-model/$DOMID/$EMULATOR_ID.
Currently two emulator_ids are statically allocated: one for device models and
one for pv qemus.

Add a parameter to libxl__device_model_xs_path to distinguish the device
model from the pv backends provider.

Store the device model binary path under
/local/domain/$DOMID/device-model on xenstore, so that we can fetch it
later and retrieve the list of supported options from
/local/domain/$LIBXL_TOOLSTACK_DOMID/libxl/$device_model_binary,
introduce in the previous path.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>

---

Changes in v4:
- update xenstore-paths.markdown

Changes in v3:
- use LIBXL_TOOLSTACK_DOMID instead of 0 in the commit message
- change xs path to include the emulator_id
---
 docs/misc/xenstore-paths.markdown |   16 +++++++++++-----
 tools/libxl/libxl.c               |    2 +-
 tools/libxl/libxl_create.c        |    3 +++
 tools/libxl/libxl_device.c        |    2 +-
 tools/libxl/libxl_dm.c            |   18 ++++++++++--------
 tools/libxl/libxl_dom.c           |   12 ++++++------
 tools/libxl/libxl_internal.c      |   19 +++++++++++++++----
 tools/libxl/libxl_internal.h      |    5 ++---
 tools/libxl/libxl_pci.c           |   14 +++++++-------
 9 files changed, 56 insertions(+), 35 deletions(-)

diff --git a/docs/misc/xenstore-paths.markdown 
b/docs/misc/xenstore-paths.markdown
index 99e038b..e6ed25f 100644
--- a/docs/misc/xenstore-paths.markdown
+++ b/docs/misc/xenstore-paths.markdown
@@ -115,6 +115,10 @@ The domain's own ID.
 The process ID of the device model associated with this domain, if it
 has one.
 
+#### ~/device-model = STRING [n,INTERNAL]
+
+The full device model binary path.
+
 #### ~/cpu/[0-9]+/availability = ("online"|"offline") [PV]
 
 One node for each virtual CPU up to the guest's configured
@@ -306,13 +310,15 @@ A virtual network device backend. Described by
 
 A PV console backend. Described in [console.txt](console.txt)
 
-#### ~/device-model/$DOMID/* [w]
+#### ~/device-model/$DOMID/$EMULATOR_ID/* [w]
 
 Information relating to device models running in the domain. $DOMID is
-the target domain of the device model. When the device model is running
-at the same privilege level of the guest domain, this path does not
-contain any sensitive information and becomes guest writeable. Otherwise
-it is INTERNAL.
+the target domain of the device model. $EMULATOR_ID indentifies a
+specific device model instance (multiple device model instances for the
+same domain are possible).  When the device model is running at the same
+privilege level of the guest domain, this path does not contain any
+sensitive information and becomes guest writeable. Otherwise
+it is INTERNAL
 
 #### ~/libxl/disable_udev = ("1"|"0") []
 
diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index 516713e..bca4c88 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -1035,7 +1035,7 @@ int libxl_domain_unpause(libxl_ctx *ctx, uint32_t domid)
     if (type == LIBXL_DOMAIN_TYPE_HVM) {
         uint32_t dm_domid = libxl_get_stubdom_id(ctx, domid);
 
-        path = libxl__device_model_xs_path(gc, dm_domid, domid, "/state");
+        path = libxl__device_model_xs_path(gc, false, dm_domid, domid, 
"/state");
         state = libxl__xs_read(gc, XBT_NULL, path);
         if (state != NULL && !strcmp(state, "paused")) {
             libxl__qemu_traditional_cmd(gc, domid, "continue");
diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
index a74b340..df946e2 100644
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -1002,6 +1002,9 @@ static void domcreate_bootloader_done(libxl__egc *egc,
         return;
     }
 
+    libxl__xs_write(gc, XBT_NULL, GCSPRINTF("/local/domain/%u/device-model", 
domid),
+            "%s", libxl__domain_device_model(gc, info));
+
     /* consume bootloader outputs. state->pv_{kernel,ramdisk} have
      * been initialised by the bootloader already.
      */
diff --git a/tools/libxl/libxl_device.c b/tools/libxl/libxl_device.c
index 93bb41e..aadcd08 100644
--- a/tools/libxl/libxl_device.c
+++ b/tools/libxl/libxl_device.c
@@ -1190,7 +1190,7 @@ int libxl__wait_for_device_model_deprecated(libxl__gc *gc,
     char *path;
     uint32_t dm_domid = libxl_get_stubdom_id(CTX, domid);
 
-    path = libxl__device_model_xs_path(gc, dm_domid, domid, "/state");
+    path = libxl__device_model_xs_path(gc, false, dm_domid, domid, "/state");
     return libxl__xenstore_child_wait_deprecated(gc, domid,
                                      LIBXL_DEVICE_MODEL_START_TIMEOUT,
                                      "Device Model", path, state, spawning,
diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
index 99e2553..8bd7b82 100644
--- a/tools/libxl/libxl_dm.c
+++ b/tools/libxl/libxl_dm.c
@@ -1272,9 +1272,9 @@ void libxl__spawn_stub_dm(libxl__egc *egc, 
libxl__stub_dm_spawn_state *sdss)
 retry_transaction:
     t = xs_transaction_start(ctx->xsh);
     xs_mkdir(ctx->xsh, t,
-             libxl__device_model_xs_path(gc, dm_domid, guest_domid, ""));
+             libxl__device_model_xs_path(gc, false, dm_domid, guest_domid, 
""));
     xs_set_permissions(ctx->xsh, t,
-                       libxl__device_model_xs_path(gc, dm_domid,
+                       libxl__device_model_xs_path(gc, false, dm_domid,
                                                    guest_domid, ""),
                        perm, ARRAY_SIZE(perm));
     if (!xs_transaction_end(ctx->xsh, t, 0))
@@ -1435,7 +1435,7 @@ static void stubdom_pvqemu_cb(libxl__egc *egc,
     sdss->xswait.what = GCSPRINTF("Stubdom %u for %u startup",
                                   dm_domid, sdss->dm.guest_domid);
     sdss->xswait.path =
-        libxl__device_model_xs_path(gc, dm_domid, sdss->dm.guest_domid,
+        libxl__device_model_xs_path(gc, true, dm_domid, sdss->dm.guest_domid,
                                     "/state");
     sdss->xswait.timeout_ms = LIBXL_STUBDOM_START_TIMEOUT * 1000;
     sdss->xswait.callback = stubdom_xswait_cb;
@@ -1571,7 +1571,8 @@ void libxl__spawn_local_dm(libxl__egc *egc, 
libxl__dm_spawn_state *dmss)
         free(path);
     }
 
-    path = libxl__device_model_xs_path(gc, LIBXL_TOOLSTACK_DOMID, domid, "");
+    path = libxl__device_model_xs_path(gc, b_info->type == 
LIBXL_DOMAIN_TYPE_PV,
+            LIBXL_TOOLSTACK_DOMID, domid, "");
     if (b_info->device_model_version == LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN &&
         libxl__check_qemu_supported(gc, dm, "xsrestrict")) {
         rwperm[0].id = LIBXL_TOOLSTACK_DOMID;
@@ -1629,8 +1630,9 @@ retry_transaction:
         LIBXL__LOG(CTX, XTL_DEBUG, "  %s", *arg);
 
     spawn->what = GCSPRINTF("domain %d device model", domid);
-    spawn->xspath = libxl__device_model_xs_path(gc, LIBXL_TOOLSTACK_DOMID,
-                                                domid, "/state");
+    spawn->xspath = libxl__device_model_xs_path(gc,
+            b_info->type == LIBXL_DOMAIN_TYPE_PV, LIBXL_TOOLSTACK_DOMID,
+            domid, "/state");
     spawn->timeout_ms = LIBXL_DEVICE_MODEL_START_TIMEOUT * 1000;
     spawn->pidpath = GCSPRINTF("%s/image/device-model-pid", dom_path);
     spawn->midproc_cb = libxl__spawn_record_pid;
@@ -1763,7 +1765,7 @@ void libxl__spawn_qdisk_backend(libxl__egc *egc, 
libxl__dm_spawn_state *dmss)
     dmss->build_state->saved_state = 0;
 
     dmss->spawn.what = GCSPRINTF("domain %u Qdisk backend", domid);
-    dmss->spawn.xspath = GCSPRINTF("device-model/%u/state", domid);
+    dmss->spawn.xspath = libxl__device_model_xs_path(gc, true, 0, domid, 
"/state");
     dmss->spawn.timeout_ms = LIBXL_DEVICE_MODEL_START_TIMEOUT * 1000;
     /*
      * We cannot save Qemu pid anywhere in the xenstore guest dir,
@@ -1846,7 +1848,7 @@ out:
 
 int libxl__destroy_device_model(libxl__gc *gc, uint32_t domid)
 {
-    char *path = libxl__device_model_xs_path(gc, LIBXL_TOOLSTACK_DOMID,
+    char *path = libxl__device_model_xs_path(gc, false, LIBXL_TOOLSTACK_DOMID,
                                              domid, "");
     if (!xs_rm(CTX->xsh, XBT_NULL, path))
         LOG(ERROR, "xs_rm failed for %s", path);
diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
index c8523da..a2bf33b 100644
--- a/tools/libxl/libxl_dom.c
+++ b/tools/libxl/libxl_dom.c
@@ -1016,7 +1016,7 @@ int libxl__qemu_traditional_cmd(libxl__gc *gc, uint32_t 
domid,
 {
     char *path = NULL;
     uint32_t dm_domid = libxl_get_stubdom_id(CTX, domid);
-    path = libxl__device_model_xs_path(gc, dm_domid, domid, "/command");
+    path = libxl__device_model_xs_path(gc, false, dm_domid, domid, "/command");
     return libxl__xs_write(gc, XBT_NULL, path, "%s", cmd);
 }
 
@@ -1034,7 +1034,7 @@ static inline char *restore_helper(libxl__gc *gc, 
uint32_t dm_domid,
                                    uint32_t domid,
                                    uint64_t phys_offset, char *node)
 {
-    return libxl__device_model_xs_path(gc, dm_domid, domid,
+    return libxl__device_model_xs_path(gc, false, dm_domid, domid,
                                        "/physmap/%"PRIx64"/%s",
                                        phys_offset, node);
 }
@@ -1146,9 +1146,9 @@ static void 
domain_suspend_switch_qemu_xen_traditional_logdirty
 
     if (!lds->cmd_path) {
         uint32_t dm_domid = libxl_get_stubdom_id(CTX, domid);
-        lds->cmd_path = libxl__device_model_xs_path(gc, dm_domid, domid,
+        lds->cmd_path = libxl__device_model_xs_path(gc, false, dm_domid, domid,
                                                     "/logdirty/cmd");
-        lds->ret_path = libxl__device_model_xs_path(gc, dm_domid, domid,
+        lds->ret_path = libxl__device_model_xs_path(gc, false, dm_domid, domid,
                                                     "/logdirty/ret");
     }
     lds->cmd = enable ? "enable" : "disable";
@@ -1672,7 +1672,7 @@ static inline char *physmap_path(libxl__gc *gc, uint32_t 
dm_domid,
                                  uint32_t domid,
                                  char *phys_offset, char *node)
 {
-    return libxl__device_model_xs_path(gc, dm_domid, domid,
+    return libxl__device_model_xs_path(gc, false, dm_domid, domid,
                                        "/physmap/%s/%s",
                                        phys_offset, node);
 }
@@ -1696,7 +1696,7 @@ int libxl__toolstack_save(uint32_t domid, uint8_t **buf,
     dm_domid = libxl_get_stubdom_id(CTX, domid);
 
     entries = libxl__xs_directory(gc, 0,
-                libxl__device_model_xs_path(gc, dm_domid, domid, "/physmap"),
+                libxl__device_model_xs_path(gc, false, dm_domid, domid, 
"/physmap"),
                 &num);
     count = num;
 
diff --git a/tools/libxl/libxl_internal.c b/tools/libxl/libxl_internal.c
index c2c67bd..5836742 100644
--- a/tools/libxl/libxl_internal.c
+++ b/tools/libxl/libxl_internal.c
@@ -567,14 +567,25 @@ void libxl__update_domain_configuration(libxl__gc *gc,
     dst->b_info.video_memkb = src->b_info.video_memkb;
 }
 
-char *libxl__device_model_xs_path(libxl__gc *gc, uint32_t dm_domid,
+char *libxl__device_model_xs_path(libxl__gc *gc, bool pvqemu, uint32_t 
dm_domid,
                                   uint32_t domid, const char *format,  ...)
 {
     char *s, *fmt;
     va_list ap;
-
-    fmt = GCSPRINTF("/local/domain/%u/device-model/%u%s", dm_domid,
-                    domid, format);
+    char *dm;
+    int emulator_id = 0;
+
+    dm = libxl__xs_read(gc, XBT_NULL, 
GCSPRINTF("/local/domain/%u/device-model", domid));
+    if (dm)
+        emulator_id = libxl__check_qemu_supported(gc, dm, "emulator_id");
+
+    if (!emulator_id) {
+        fmt = GCSPRINTF("/local/domain/%u/device-model/%u%s", dm_domid,
+                domid, format);
+    } else {
+        fmt = GCSPRINTF("/local/domain/%u/device-model/%u/%u%s", dm_domid,
+                domid, pvqemu ? QEMU_XEN_PV_ID : QEMU_XEN_DEVICE_MODEL_ID, 
format);
+    }
 
     va_start(ap, format);
     s = libxl__vsprintf(gc, fmt, ap);
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index b4bae2f..e15cdc7 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -1830,9 +1830,8 @@ _hidden libxl__json_object *libxl__json_parse(libxl__gc 
*gc_opt, const char *s);
 _hidden int libxl__device_model_version_running(libxl__gc *gc, uint32_t domid);
   /* Return the system-wide default device model */
 _hidden libxl_device_model_version libxl__default_device_model(libxl__gc *gc);
-_hidden char *libxl__device_model_xs_path(libxl__gc *gc, uint32_t dm_domid,
-                                          uint32_t domid,
-                                          const char *format, ...) 
PRINTF_ATTRIBUTE(4, 5);
+_hidden char *libxl__device_model_xs_path(libxl__gc *gc, bool pvqemu, uint32_t 
dm_domid,
+                                  uint32_t domid, const char *format,  ...);
 
 /* Check how executes hotplug script currently */
 int libxl__hotplug_settings(libxl__gc *gc, xs_transaction_t t);
diff --git a/tools/libxl/libxl_pci.c b/tools/libxl/libxl_pci.c
index e0743f8..07f6209 100644
--- a/tools/libxl/libxl_pci.c
+++ b/tools/libxl/libxl_pci.c
@@ -853,9 +853,9 @@ static int qemu_pci_add_xenstore(libxl__gc *gc, uint32_t 
domid,
     uint32_t dm_domid;
 
     dm_domid = libxl_get_stubdom_id(CTX, domid);
-    path = libxl__device_model_xs_path(gc, dm_domid, domid, "/state");
+    path = libxl__device_model_xs_path(gc, false, dm_domid, domid, "/state");
     state = libxl__xs_read(gc, XBT_NULL, path);
-    path = libxl__device_model_xs_path(gc, dm_domid, domid, "/parameter");
+    path = libxl__device_model_xs_path(gc, false, dm_domid, domid, 
"/parameter");
     if (pcidev->vdevfn) {
         libxl__xs_write(gc, XBT_NULL, path, PCI_BDF_VDEVFN","PCI_OPTIONS,
                         pcidev->domain, pcidev->bus, pcidev->dev,
@@ -870,9 +870,9 @@ static int qemu_pci_add_xenstore(libxl__gc *gc, uint32_t 
domid,
     libxl__qemu_traditional_cmd(gc, domid, "pci-ins");
     rc = libxl__wait_for_device_model_deprecated(gc, domid, NULL, NULL,
                                       pci_ins_check, state);
-    path = libxl__device_model_xs_path(gc, dm_domid, domid, "/parameter");
+    path = libxl__device_model_xs_path(gc, false, dm_domid, domid, 
"/parameter");
     vdevfn = libxl__xs_read(gc, XBT_NULL, path);
-    path = libxl__device_model_xs_path(gc, dm_domid, domid, "/state");
+    path = libxl__device_model_xs_path(gc, false, dm_domid, domid, "/state");
     if ( rc < 0 )
         LIBXL__LOG(ctx, LIBXL__LOG_ERROR,
                    "qemu refused to add device: %s", vdevfn);
@@ -1178,9 +1178,9 @@ static int qemu_pci_remove_xenstore(libxl__gc *gc, 
uint32_t domid,
 
     dm_domid = libxl_get_stubdom_id(CTX, domid);
 
-    path = libxl__device_model_xs_path(gc, dm_domid, domid, "/state");
+    path = libxl__device_model_xs_path(gc, false, dm_domid, domid, "/state");
     state = libxl__xs_read(gc, XBT_NULL, path);
-    path = libxl__device_model_xs_path(gc, dm_domid, domid, "/parameter");
+    path = libxl__device_model_xs_path(gc, false, dm_domid, domid, 
"/parameter");
     libxl__xs_write(gc, XBT_NULL, path, PCI_BDF, pcidev->domain,
                     pcidev->bus, pcidev->dev, pcidev->func);
 
@@ -1198,7 +1198,7 @@ static int qemu_pci_remove_xenstore(libxl__gc *gc, 
uint32_t domid,
             return ERROR_FAIL;
         }
     }
-    path = libxl__device_model_xs_path(gc, dm_domid, domid, "/state");
+    path = libxl__device_model_xs_path(gc, false, dm_domid, domid, "/state");
     xs_write(ctx->xsh, XBT_NULL, path, state, strlen(state));
 
     return 0;
-- 
1.7.10.4


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